inherently inherently oxygen limited due to diffusional constraints, rather than limited by electron donor or Ca availability. Such oxygen limitation will limit MICP in all water-saturated and oxygen-dependent systems, and MICP agents based on anaerobic bacteria, e.g., nitrate reducers, should be developed to broaden the applicability of bioactive self-healing concretes to wet and waterlogged environments.

Nikolova, C., Gutierrez, T., 2020. Use of microorganisms in the recovery of oil from recalcitrant oil reservoirs: Current state of knowledge, technological advances and future perspectives. Frontiers in Microbiology 10, 2996. doi: 10.3389/fmicb.2019. 02996.

https://www.frontiersin.org/article/10.3389/fmicb.2019.02996 The depletion of oil resources, increasing global energy demand, the current low, yet unpredictable, price of oil, and increasing maturity of major oil fields has driven the need for the development of oil recovery technologies that are less costly and, where possible, environmentally compatible. Using current technologies, between 20 and 40% of the original oil in a reservoir can be extracted by conventional production operations (e.g., vertical drilling), with secondary recovery methods yielding a further 15 - 25%. Hence, up to 55% of the original oil can remain unrecovered in a reservoir. Enhanced oil recovery (EOR) is a tertiary recovery process that involves application of different thermal, chemical, and microbial processes to recover an additional 7 - 15% of the original oil in place (OOIP) at an economically feasible production rate from poor-performing and depleted oil wells. EOR can significantly impact oil production, as increase in the recovery rate of oil by even a small margin could bring significant revenues without developing unconventional resources. Microbial enhanced oil recovery (MEOR) is an attractive, alternative oil recovery approach, which is claimed to potentially recover up in situ to 50% of residual oil. The production of biological surface-active compounds (e.g., biosurfactants) during the MEOR process does not require vast energy inputs and are not affected by global crude oil prices. Compared to other EOR methods, MEOR can be an economically and more environmentally friendly alternative. In this review, the current state of knowledge of MEOR, with insights from discussions with the industry and other stakeholders, is presented and in addition to the future outlook for this technology.

Nomchong, B.J., Van Kranendonk, M.J., 2020. Diverse thrombolites from the c. 2.4 Ga Turee Creek Group, Western Australia. Precambrian Research 338, 105593.

http://www.sciencedirect.com/science/article/pii/S0301926819301858 Observations from a stromatolite-thrombolite reef complex of the c. 2.4 Ga Turee Creek Group, Western Australia, indicate diversity in stromatolite and microfossil morphology, in addition to the appearance of clotted (thrombolite-like) microbialites (Barlow et al., 2016, Barlow and Van Kranendonk, 2018). Here, we document the diverse morphologies and textures of clotted microbialites from the Turee Creek Group reef complex that occur interbedded and interlayered with stromatolites and sediments in the supratidal to subtidal facies. The clotted microbialites consist of four types with distinct gross morphology, mesostructure, and microtextures, including: 1) an aggregate of isolated, millimetre-scale organic-rich clots that accumulated following storm events and were cemented by coarsely crystalline radiating carbonate; 2) domal bioherms composed of a framework of non-laminated branching columns; 3) stratiform clotted microbialites consisting of fine-grained clots that form both an interconnected framework surrounded by coarsely crystalline cement, or comprise a poorly-defined mixture of fine- and coarsely crystalline textural components; and 4) thrombolites that comprise lobate bioherms with non-layered internal textures. Variations in thrombolite texture and morphology are likely driven by a combination of environmental and biological factors, as is the case in modern microbial carbonate environments, such as Shark Bay and the Bahamas. These findings show that the Turee Creek Group clotted microbialites are significantly more diverse than first recognised, adding to previously documented expressions of microbialite complexity from this microbialite reef complex.

Norouzi, N., Fani, M., Ziarani, Z.K., 2020. The fall of oil Age: A scenario planning approach over the last peak oil of human history by 2040. Journal of Petroleum Science and Engineering 188, 106827.

http://www.sciencedirect.com/science/article/pii/S092041051931246X